Merge 8b8cf9e into 4cfae3f

mmdet3d/datasets/transforms/formating.py

@@ -147,15 +147,19 @@ def pack_single_results(self, results: dict) -> dict:
  if 'img' in results:
  if isinstance(results['img'], list):
  # process multiple imgs in single frame
- imgs = [img.transpose(2, 0, 1) for img in results['img']]
- imgs = np.ascontiguousarray(np.stack(imgs, axis=0))
+ imgs = [to_tensor(img) for img in results['img']]
+ imgs = torch.stack(
+ imgs, dim=0).permute(0, 3, 1, 2).contiguous()
  results['img'] = to_tensor(imgs)
  else:
  img = results['img']
  if len(img.shape) < 3:
  img = np.expand_dims(img, -1)
- results['img'] = to_tensor(
- np.ascontiguousarray(img.transpose(2, 0, 1)))
+ # To improve the computational speed by by 3-5 times, apply:
+ # `torch.permute()` rather than `np.transpose()`.
+ # Refer to https://github.com/open-mmlab/mmdetection/pull/9533
+ # for more details
+ results['img'] = to_tensor(img).permute(2, 0, 1).contiguous()
 
  for key in [
  'proposals', 'gt_bboxes', 'gt_bboxes_ignore', 'gt_labels',